The present invention relates to a train which forms a transport device displaceable along a fixed track, comprising:
a frame with a drive;
at least one bogie with a flat sole; and
at least one supply of a liquid which is suitable for pouring the liquid over the track, wherein at a speed of the train higher than a threshold value at least a part of the sole floats over a film created by the liquid.
Such a train is known from the British patent specification 5.569 in which such a configuration of a train is described, wherein transport is made possible particularly as a result of the upward force of the liquid which is generated by a compressor and which is directed under the sole to discharge the liquid under pressure here via the supply.
According to the prior art the pressure to be generated by this compressor must be maintained even when an aquaplaning effect occurs above a determined speed, wherein a part of the bottom surface of the sole floats over a water film. A drawback associated herewith is that a heavy compressor is required, wherein as a result of the configuration of the prior art, too much water or another liquid is lost precisely as a consequence of the high pressure to enable transport over a distance which is usual in practice.
A further drawback is that the supply debouches under the sole. At a high speed there is the danger here that the part of the surface of the sole located at the front in the direction of movement of the train is deprived of water or other liquid, which does not reach this front part of the surface of the sole, precisely as a result of this high speed and thereby insufficient pressure. In this situation that part of the surface of the sole deprived of liquid will come into contact with the surface of the track because no liquid film lies therebetween. In this situation the train will travel in a jolting manner until the speed is sufficiently reduced and the liquid under pressure can once again reach the front part of the surface of the sole on the track. The damage which can hereby be caused to track and sole is considerable.
The invention has for its object to obviate at least one of the above stated problems and a train is provided for this purpose which is distinguished in that the supply is adapted to carry the liquid onto the track in front of the sole in the direction of movement of the train, and that the sole is positioned inclining upward on the front side in the direction of movement.
In this manner is ensured that at any speed above the threshold value the entire sole is involved in the aquaplaning effect, wherein the entire sole slides above the track, floating on the liquid film. Further achieved, in combination with the form of the track, is that only a very small quantity of liquid is required to realize the liquid film, wherein this liquid moreover does not have to be delivered at high pressure under the sole but, on the contrary, can simply be deposited on the track practically without pressure. As already stated above, small quantities of liquid can herein suffice to bring about the intended effect. The track can moreover be cleaned during application of the liquid, which is herein sprayed over the track under some pressure. The sole is further positioned inclining upward at the front in order to bring the largest possible quantity of liquid under the sole, wherein a progressively smaller space or volume in rearward direction is available, so that an equilibrium results between the force of the water on the sole and vice versa.
In a first embodiment a train according to the present invention has the property that the bogie is arranged for free tilting on the train at least in the direction of movement thereof, wherein the tilting point of the bogie is positioned in the direction of movement behind the centre of the length of the sole and in front of the maximum of the upward pressure on the bogie generated at the higher speed by the liquid film. As a result of the ability of the sole to tilt freely, a self-adjustment of the position of the sole is effected depending on the pressure on the sole and on the speed of the train. This is the case because the total moment acting at a determined speed on the part of the sole in front of the tilting point in the direction of movement is in equilibrium with the total moment exerted on the part of the sole behind the tilting point. The front part of the sole is herein directed slightly upward, wherein the tilting point is situated just behind the centre of the length of the sole and the sole encloses a relatively thick liquid film on the front side.
In a second embodiment a train according to the present invention has the property that the sole forms a sliding surface, wherein the sliding surface preferably contains grooves lying in the direction of locomotion of the train. Thus is achieved that respectively for the sole designed as sliding surface a large support surface is provided on the water film spread on the track and that even distribution of the water film is obtained by means of the grooves. In an embodiment of the train according to the invention has the property that the grooves are designed narrowing in rearward direction relative to the direction of locomotion. More of the liquid lying on the track is hereby enclosed beneath the sliding surface and pressed out of the grooves in downward direction along the length of the grooves so as to have a favourable influence on the upward force generated by the water film.
In a third embodiment of the present invention a train according to the present invention has the property that at least one supplementary supply of additional liquid is arranged in the bogie and debouches under the sole. In this manner a per se known configuration is obtained, which is however only used or set into operation as long as the threshold value of the speed is not yet reached by the moving train. Possible losses can also be replenished using the supplementary supply, which is particularly relevant when the train is one with a number of successively arranged bogies which, in respect of the liquid film, are all dependent on a collective supply at the front part of the train in front of the leading bogie.
In a fourth embodiment a train according to the present invention has the property that at least one conduit is arranged in the bogie which debouches under the sole for supply of a fluid with a lower viscosity than the liquid. Use can herein be made of for instance gas as fluid, wherein as a result of supplying this fluid with a lower viscosity than the liquid the aquaplaning effect is better utilized, wherein the sole floats over the liquid with the fluid thereon on the track, so that the movement resistance is decreased. The fluid therefore preferably also has a lower density, so that is remains lying on the liquid, this already being ensured particularly when gas is used as fluid.
In a fifth embodiment a train according to the present invention has the property that the sole is divided into at least two areas which are enclosed by downward extending peripheries of resilient material substantially along the circumference of each of the areas. In preference each of the two areas can be separately provided herein with liquid and optionally fluid, so that control of the position of the sole in lateral direction, in the direction of locomotion of the train or both can be hereby obtained or improved, so that adjustment of this position can be optimized subject to the speed under the influence of an active control. The peripheries manufactured of resilient material are provided to minimize losses, whereby as much of the supplied liquid and the supplied fluid as possible can be used efficiently without flowing directly out of the space under the sole, whereby losses occur.
The invention otherwise also relates to a track for a train according to any of the foregoing claims which comprises at least one platform extending in horizontal direction. This track is also known from the above mentioned publication of the British patent specification 5.569, wherein this track results in considerable losses as a result of the inherent properties thereof, and particularly the deficient smoothness thereof.
A track according to the present invention is distinguished in that the platform is coated with a levelling material, wherein an upper surface of the track has a very high degree of smoothness with very small height differences. As a result of the properties of the track provided here according to the invention, losses as a result of unevenness are minimized. In order to obtain the desired smoothness or evenness use can preferably be made of ultra high molecular weight polyethylene, with which a very high degree of evenness can be realized.
In a first embodiment a track according to the present invention has the property that a guide extending in upward direction is arranged along the longitudinal axis of the track, which guide comprises engaging means on at least one side for co-action with the drive of the train. Because the guide extends along the longitudinal axis of the track, engagement for the purpose of driving takes place at least close to the centre of the track, so that a possible asymmetrical distribution of forces and pitching sideways of the train as a result thereof is prevented in effective manner.
As a possible second embodiment, the engaging means preferably comprise at least one gear rack path, wherein the drive comprises at least one toothed wheel co-acting with the gear rack path and connected to a motor. This is therefore an embodiment which is simple of realization, entails relatively low cost and which preferably comprises a two-sided central drive. Alternatively, it is possible within the scope of this embodiment that a guide extending in upward direction is arranged along the longitudinal axis of the track and that the track or the guide comprises means co-acting with a contact-free driving of the train, such as a magnetic drive. It is obvious that the drive for reaching and maintaining the speed required for aquaplaning can be realized in many ways.
In a third embodiment a track according to the present invention is characterized by at least one supply of liquid connectable to a bogie of the train. The supply of liquid has the advantage that in order to be moved the train itself does not have to be provided with a tank or similar means other than for instance an emergency tank from which liquid can be drawn in the case that the supply in the track provides no or insufficient liquid.
The same applies in a fourth embodiment of a track according to the invention which is characterized by at least one conduit of fluid connectable to a bogie of the train or by power conductors connectable to the train for transport of electrical power to the train. In the latter case the need for an overhead line is dispensed with.